.\" Copyright (c) 1993
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.\"	@(#)err.3	8.1.1 (2.11BSD GTE) 2/3/95
.\"
.TH ERR 3 "February 3, 1995"
.UC 4
.SH NAME
err,
verr ,
errx ,
verrx ,
warn ,
vwarn ,
warnx ,
vwarnx \- formatted error messages
.SH SYNOPSIS
.nf
.ft B
void
err(eval, fmt, ...)
    int eval;
    char *fmt;
.PP
void
verr(eval, fmt, args)
    int eval;
    char *fmt;
    va_list args;
.PP
void
errx(eval, fmt, ...)
    int eval;
    char *fmt;
.PP
void
verrx(eval, fmt, args)
    int eval
    char *fmt;
    va_list args;
.PP
void
warn(fmt, ...)
    char *fmt;
.PP
void
vwarn(fmt, args)
    char *fmt;
    va_list args;
.PP
void
warnx(fmt, ...)
    char *fmt;
.PP
void
vwarnx(fmt, args)
    char *fmt;
    va_list args;
.ft R
.fi
.SH DESCRIPTION
The
.B err
and
.B warn
family of functions display a formatted error message on the standard
error output.
In all cases, the last component of the program name, a colon character,
and a space are output.
If the
.I fmt
argument is not NULL, the formatted error message, a colon character,
and a space are output.
In the case of the
.BR err ,
.BR verr ,
.BR warn ,
and
.BR vwarn
functions, the error message string affiliated with the current value of
the global variable
.I errno 
is output.
In all cases, the output is followed by a newline character.
.PP
The
.BR err ,
.BR verr ,
.BR errx ,
and
.BR verrx
functions do not return, but exit with the value of the argument
.IR eval .
.SH EXAMPLES
Display the current errno information string and exit:
.sp
.in +1.0i
.nf
if ((p = malloc(size)) == NULL)
	err(1, NULL);
if ((fd = open(file_name, O_RDONLY, 0)) == -1)
	err(1, "%s", file_name);
.in -1.0i
.fi
.PP
Display an error message and exit:
.sp
.in +1.0i
.nf
if (tm.tm_hour < START_TIME)
	errx(1, "too early, wait until %s", start_time_string);
.in -1.0i
.fi
.PP
Warn of an error:
.sp
.in +1.0i
.nf
if ((fd = open(raw_device, O_RDONLY, 0)) == -1)
	warnx("%s: %s: trying the block device",
	    raw_device, strerror(errno));
if ((fd = open(block_device, O_RDONLY, 0)) == -1)
	err(1, "%s", block_device);
.in -1.0i
.fi
.SH SEE ALSO
strerror(3)
.SH HISTORY
The
.B err
and
.B warn
functions first appeared in 4.4BSD.
